U.S. patent number 7,998,146 [Application Number 11/673,627] was granted by the patent office on 2011-08-16 for apparatus and method for hip cup extraction.
This patent grant is currently assigned to Innomed, Inc.. Invention is credited to James Anderson.
United States Patent |
7,998,146 |
Anderson |
August 16, 2011 |
Apparatus and method for hip cup extraction
Abstract
A hip cup extraction apparatus (101) comprising a shaft (402), a
handle (404), a semicircular cutting blade (406), a spring loaded
latching member (408), and a head (100) for removing a hip cup
(405) from a pelvic bone (401). The head (100) includes a
semispherical section (102) terminating in a substantially planar
surface (104), a hip cup extraction apparatus aperture (106), a
retaining sleeve (108), and a three sided void (110). The head
(100) may be configured for selective attachment to the hip cup
extraction apparatus (101). The hip cup extraction apparatus (101)
is inserted into the hip cup extraction apparatus aperture (106),
and an optional spring loaded latching member (408) retains the
head (100) in place. As the head (100) is being attached to the hip
cup extraction apparatus (101), the semicircular cutting blade
(406) may pass through the three sided void (110). Once the head
(100) is attached to the hip cup extraction apparatus (101), the
head (100) is inserted into the hip cup (405). Force may then be
applied to the hip cup extraction apparatus (101) in order to drive
the semicircular cutting blade (406) into the pelvic bone (401).
The hip cup extraction apparatus (101) may then be rotated or
pivoted such that the semicircular cutting blade (406) passes
completely around the hip cup (405).
Inventors: |
Anderson; James (Savannah,
GA) |
Assignee: |
Innomed, Inc. (Savannah,
GA)
|
Family
ID: |
39686503 |
Appl.
No.: |
11/673,627 |
Filed: |
February 12, 2007 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20080195111 A1 |
Aug 14, 2008 |
|
Current U.S.
Class: |
606/99;
606/91 |
Current CPC
Class: |
A61B
17/1666 (20130101); A61F 2/4609 (20130101); A61F
2002/30616 (20130101); A61F 2002/30505 (20130101); A61F
2/34 (20130101); A61F 2002/30331 (20130101); A61F
2220/0025 (20130101); A61F 2002/4619 (20130101); A61F
2220/0033 (20130101) |
Current International
Class: |
A61B
17/58 (20060101); A61B 17/60 (20060101); A61F
2/00 (20060101) |
Field of
Search: |
;606/81,82,86,91,99,99R
;623/22.21,21,19,18 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Sales brochure, Innomed, "Universal Hip Cup Removal System", 2006.
cited by other.
|
Primary Examiner: Barrett; Thomas C
Assistant Examiner: Boles; Sameh
Attorney, Agent or Firm: Burrus, IV; Philip H.
Claims
What is claimed is:
1. A head configured for selective attachment to a hip cup
extraction apparatus having a shaft and a cutting blade extending
outwardly from a side of the shaft, the head comprising: a
semispherical section terminating in a substantially planar
surface, the semispherical section having a spherical section
diameter of between 39 and 60 millimeters; a hip cup extraction
apparatus aperture disposed centrally along the substantially
planar surface; a retaining sleeve projecting distally from the
substantially planar surface about the hip cup extraction apparatus
aperture configured to receive an end of the shaft; and a three
sided void disposed along the semispherical section; wherein the
three sided void is configured such that when the head is being
coupled to the shaft, a tip of the cutting blade may pass through
the three sided void without mechanical interference.
2. The head of claim 1, wherein the head is manufactured from one
of stainless steel or acetal resin plastic.
3. The head of claim 1, wherein the hip cup extraction apparatus
aperture has an aperture diameter of between 12 and 18
millimeters.
4. The head of claim 3, wherein the aperture diameter of the hip
cup extraction apparatus aperture is between 15.784 and 16.002
millimeters.
5. The head of claim 1, wherein the three sided void is
characterized by a width of between 7 and 12 millimeters.
6. The head of claim 1, wherein the head further comprises a
cylindrical detente disposed about the hip cup extraction apparatus
aperture.
7. The head of claim 6, wherein the cylindrical detente has a
diameter of between 11.296 and 11.557 millimeters.
8. The head of claim 1, wherein the retaining sleeve projects
distally from the substantially planar surface by at least 9
millimeters.
9. The head of claim 1, wherein a first side of the three sided
void is less than 18 millimeters from a center of the head.
10. A cutting apparatus for removing a hip cup from a pelvic bone,
comprising: a shaft having a length of at least 275 millimeters; a
handle extending distally from the shaft; a semicircular cutting
blade coupled to the shaft, wherein the semicircular cutting blade
projects outwardly from a side of the shaft; a spring loaded
latching member coupled to the shaft between the semicircular
cutting blade and a first end of the shaft; and a head comprising a
semispherical section terminating in a substantially planar
surface, and a three sided void disposed along the semispherical
section; wherein the three sided void is configured such that when
the head is being coupled to the first end of the shaft, a tip of
the semicircular blade may pass through the three sided void.
11. The cutting apparatus of claim 10, wherein the handle is
disposed at a distal end of the shaft relative to the head.
12. The cutting apparatus of claim 10, further comprising an
impaction platform disposed at a second end of the shaft.
13. The cutting apparatus of claim 10, wherein the semicircular
cutting blade terminates between 17 and 20 millimeters from a
radial center of the shaft.
14. The cutting apparatus of claim 10, wherein the shaft is
manufactured from metal.
15. The cutting apparatus of claim 10, wherein the semispherical
section of the head has a spherical section diameter of between 39
and 60 millimeters.
16. The cutting apparatus of claim 10, wherein one side of the
three sided void is within 17.12 millimeters of a center of the
shaft when measured along a line normal to the one side.
17. The cutting apparatus of claim 16, wherein the three sided void
is characterized by a width of between 7 and 12 millimeters.
18. The cutting apparatus of claim 10, wherein the head is
selectively detachable.
19. The cutting apparatus of claim 10, wherein at least two sides
of the three sided void are oriented parallel with the shaft.
Description
BACKGROUND
1. Technical Field
This invention relates generally to an apparatus and method for
removing a prosthetic hip cup from a pelvic bone, and more
specifically to a tool having interchangeable heads for removing
hip cups having different dimensions.
2. Background Art
Over the years, advances in medical procedures have helped
countless people live normal lives after suffering devastating
ailments. One such area of advancement has been in the field of
orthopedic medicine, which is the curing of disorders of the
musculoskeletal system. In particular, progress in the field hip
replacement has been very important to helping those with mobility
problems caused by hip damage.
One common type of hip ailment is the loss of cartilage in the hip
sockets, which hold rotary balls attached to the femur bones. This
relationship between the hip sockets and the rotary balls enables a
person to walk and perform other movement of the legs. In a healthy
hip, the cartilage present in the hip socket acts as a cushion that
enables the rotary ball to move freely in the hip socket. As this
cartilage deteriorates, sometimes with age and sometimes with
disease, the rotary ball may begin to rub against the bone surface
of the hip socket thereby causing bone on bone grinding. This
grinding may be very painful.
To help people with damaged cartilage in their hips, doctors
sometimes replace the rotary ball of the femur with a prosthetic
rotary device, and insert a prosthetic hip cup into the pelvic
bone. The prosthetic rotary device then fits within the prosthetic
hip cup, and works as an artificial hip. Over time, these
prosthetic pieces may become worn and may need to be replaced.
Tools to replace the prosthetic hip cup are known in the art. The
problem with these prior art replacement tools, however, is that
they are typically designed for only one type or size of hip cup.
For instance, they may be designed to work with only one
manufacturer's cup or one size cup.
In recent years, new hip cup designs have been introduced. In
general, these designs are made by different manufacturers and in
different sizes. Because of their varying sizes, tools used to
replace the specific hip cups are not suitable for use with these
varying sized cup implants. For example, when a tool designed to
remove the small hip cup is used to remove a larger hip cup, the
tool may not seat properly within the cup, thereby making the
cutting process erratic and haphazard.
There is thus a need for an improved hip cup removal device
suitable for use with hip cups of varying sizes.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying figures, where like reference numerals refer to
identical or functionally similar elements throughout the separate
views and which together with the detailed description below are
incorporated in and form part of the specification, serve to
further illustrate various embodiments and to explain various
principles and advantages all in accordance with the present
invention.
FIG. 1 illustrates one embodiment of a detachable head configured
for selective attachment to a hip cup extraction apparatus in
accordance with the invention.
FIG. 2 illustrates a top plan view of a detachable head in
accordance with one embodiment of the invention.
FIG. 3 illustrates a table showing various dimensions of a
detachable head suitable for use with a hip cup extraction
apparatus in accordance with embodiments of the invention.
FIG. 4 illustrates one embodiment of the hip cup extraction device
in accordance with the invention.
FIG. 5 illustrates one embodiment of a method for removing a
prosthetic hip cup from a pelvic bone using a hip cup extraction
device in accordance with the invention.
FIG. 6 illustrates a hip cup extraction device in accordance with
embodiments of the invention.
FIG. 7 illustrates a hip cup extraction device in accordance with
embodiments of the invention.
Skilled artisans will appreciate that elements in the figures are
illustrated for simplicity and clarity and have not necessarily
been drawn to scale. For example, the dimensions of some of the
elements in the figures may be exaggerated relative to other
elements to help to improve understanding of embodiments of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
Before describing in detail embodiments that are in accordance with
the present invention, it should be observed that the embodiments
reside primarily in combinations of method steps and apparatus
components related to an apparatus and method for employing a hip
cup removal apparatus using a detachable head for removing a
prosthetic hip cup from a pelvic bone. Accordingly, the apparatus
components and method steps have been represented where appropriate
by conventional symbols in the drawings, showing only those
specific details that are pertinent to understanding the
embodiments of the present invention so as not to obscure the
disclosure with details that will be readily apparent to those of
ordinary skill in the art having the benefit of the description
herein.
Embodiments of the invention are now described in detail. Referring
to the drawings, like numbers indicate like parts throughout the
views. As used in the description herein and throughout the claims,
the following terms take the meanings explicitly associated herein,
unless the context clearly dictates otherwise: the meaning of "a,"
"an," and "the" includes plural reference, the meaning of "in"
includes "in" and "on." Relational terms such as first and second,
top and bottom, and the like may be used solely to distinguish one
entity or action from another entity or action without necessarily
requiring or implying any actual such relationship or order between
such entities or actions. Also, reference designators shown herein
in parenthesis indicate components shown in a figure other than the
one in discussion. For example, talking about a device (10) while
discussing figure A would refer to an element, 10, shown in figure
other than figure A.
The invention described below generally relates to a tool and
method being used in the process of hip cup replacement. To better
understand the process with which the invention is used, below is a
brief summary of the complete process of a hip cup replacement
procedure using hip cup replacement devices in accordance with
embodiments of the present invention.
The inside and outside diameters of the prosthetic hip cup to be
removed are measured. A blade size is chosen to correspond to an
outside diameter of the cup. A spherical head size is next chosen
based on the inside diameter of the cup liner. The spherical head
corresponding to the cup size is then installed onto a shaft
configured with a short, starter blade, which begins the hip cup
removal process. The starter blade, which is shorter and stiffer
than a finishing blade (described below), is used around the top
rim of the prosthetic hip cup to remove denser bone. The head is
then seated into the old prosthetic hip cup liner. A mallet may be
used to strike an impaction platform on the end of the shaft to
help drive the blade into the pelvic bone. The shaft may then be
pivoted and/or rotated to make an orbital cut around the old
prosthetic hip cup. A handle positioned near the end of the shaft
allows for easier rotation of the instrument.
Once the starter blade has removed the outer bone around the old
prosthetic hip cup, the head may be removed from the starter blade
shaft and installed on a finishing device consisting of a shaft
having a finishing blade coupled thereto. The longer, thinner
finish blade is used for deeper cutting around the dome of the old
prosthetic hip cup. The shaft is pivoted and/or rotated is the same
manner as the starter blade device until the finishing blade
removes the bone around the old prosthetic hip cup. The old
prosthetic hip cup may now be removed from the hip so that a new
one can be inserted.
Turning now to FIG. 1, illustrated therein is one embodiment of a
head 100 configured for selective attachment to a hip cup
extraction apparatus 101. In one embodiment, the head 100 may be
manufactured from a rigid, durable material such as stainless
steel. In another embodiment, the head 100 may be manufactured from
a plastic or polymer, such as acetal resin plastic. It will be
clear to those of ordinary skill in the art having the benefit of
this disclosure that the head 100 may be manufactured from other
rigid materials such as ceramics or other metals, plastics or
polymers.
The head 100 comprises a semispherical section 102 which terminates
in a substantially planar surface 104. As used herein, the term
"semispherical" does not necessarily mean hemispherical. For the
purpose of this invention, semispherical is defined as being a
range of shapes that may be less than half a sphere, or may be
greater than half a sphere. In one embodiment, the semispherical
section 102 of the head 100 has a spherical section diameter 103 of
between 39 millimeters and 60 millimeters.
The head 100 further comprises a hip cup extraction apparatus
aperture 106 which may be disposed centrally along the
substantially planar surface 104. When the head 100 is attached to
the hip cup extraction apparatus 101, a shaft the hip cup
extraction apparatus 101 fits inside of the hip cup extraction
apparatus aperture 106. In one embodiment, the hip cup extraction
apparatus aperture 106 has an aperture diameter 107 of between 7
millimeters and 12 millimeters. Experimental testing has shown that
an aperture diameter 107 is between 9.525 millimeters and 9.551
millimeters works well in practice.
In one embodiment, the head 100 further comprises a cylindrical
detente 116 disposed about the hip cup extraction apparatus
aperture 106. Experimental testing has shown that a cylindrical
detente 116 having a diameter of between 11.45 millimeters and
11.71 millimeters so as to accommodate a hip cup extraction
apparatus 101 having a shaft 112 with a diameter of between 10.87
millimeters and 10.97 millimeters is effective in the removal of
most commonly available hip cups. As illustrated in the exemplary
embodiment of FIG. 1, the cylindrical detente 116 may be used to
hold a spring loaded latching member 114 connected to the hip cup
extraction apparatus 101 to enable the hip cup extraction apparatus
101 to latch on to the head 100 when then head 100 is attached to
the hip cup extraction apparatus 101.
In one embodiment, the head 100 further comprises a retaining
sleeve 108, which projects distally from the substantially planar
surface 104 about the hip cup extraction apparatus aperture 106.
The retaining sleeve 108 projects distally from the substantially
planar surface 104 by at least 9 millimeters. The retaining sleeve
108 may be used to increase a head distal length 109. Increasing
the head distal length 109 may increase the length of the hip cup
extraction apparatus aperture and thus increase the length of the
hip cup extraction apparatus 101 that is inside of the hip cup
extraction apparatus aperture 106, thereby increasing the
mechanical stability between the head 100 and the shaft 112.
Turning briefly to FIG. 2, illustrated therein is a top plan view
of the head 100. As can be seen from this view, the head 100 in one
embodiment further comprises a three sided void 110 disposed along
the semispherical section 102. The three sided void comprises a
first side 201, a second side 203, and a third side 204. In one
embodiment, the first side 201 may have a length of between 7
millimeters and 12 millimeters. The first side 201 may,
alternatively, be less than 18 millimeters (measured radially) from
a center 202 of the head 100. As will be seen below, the three
sided void 110 allows the head 100 to be attached to a hip cup
extraction apparatus 101 that has a blade coupled thereto without
any mechanical interference.
Turning now to FIG. 3, illustrated therein is a table 300 showing
various dimensions of a head (100) suitable for use with
embodiments of the invention. Moreover, the table illustrates a
plurality of paired values of spherical section diameters (103) and
head distal lengths (109). Note that these values are meant to be
exemplary only. It will be clear to those of ordinary skill in the
art having the benefit of this disclosure that the spherical
section diameter 103 and the head distal length 109 are not limited
to just the respective pairings as shown in the table 300. Other
embodiments, as dictated by the hip cup size to be removed by the
invention, can equally be used. Additionally, it will be clear that
the dimensions of the spherical section diameter (103) and the head
distal length (109) are not limited to the integer values between
their respective maximum and minimum values as shown in table
300.
Now turning to FIG. 4, illustrated therein is one embodiment of the
hip cup extraction device 400. The hip cup extraction device 400
may be used for removing a hip cup 405 from a pelvic bone 401. The
hip cup extraction device 400 comprises a hip cup extraction
apparatus 101 coupled to a head 100. The hip cup extraction
apparatus 101 comprises a shaft 112 to which the head 100 may be
selectively attached. In one embodiment, the shaft 112 has a length
of at least 275 millimeters. The shaft 112 is preferably
manufactured from a rigid material such as metal. Those with
ordinary skill in the art having benefit of this disclosure will
appreciate that the shaft may be manufactured from other rigid
materials, such as plastics, polymers, and ceramics. The shaft 112
includes a first end 410 and a second, distal end 414.
The hip cup extraction apparatus 101 includes a handle 404 that
projects outward from the shaft 402. In one embodiment, the handle
404 is disposed distally from the first end 410, toward the second
end 412 of the shaft 112. The hip cup extraction apparatus 101 may
further include an impaction platform 416 disposed at, or near, the
second end 412 of the shaft 112. An impaction device, such as a
hammer or mallet, may be used to hit the impaction platform 416 to
drive the blade 406 into the pelvic bone to begin the cutting
process.
The hip cup extraction apparatus 101 has a semicircular cutting
blade 406 affixed thereto. The semicircular cutting blade 406
projects outwardly from the shaft 112. In one embodiment, the
semicircular cutting blade 406 may terminate between 17 millimeters
and 20 millimeters from a radial center of the shaft 112. Those
with ordinary skill in the art having the benefit of this
disclosure will appreciate that the semicircular cutting blade 406
may be manufactured in shapes and sizes other than that shown in
FIG. 4. For example, the semicircular cutting blade 406 may be
either a starter blade or a finishing blade. Additionally, the
semicircular cutting blade 406 may take alternate shapes as
dictated by the hip cup to be removed.
To retain the head 100 to the hip cup extraction apparatus 101, a
latching device such as a spring loaded latching member 408, may be
employed. The spring loaded latching member 408 is coupled to the
shaft 112 between the semicircular cutting blade 406 and the first
end of the shaft 402. In one embodiment, the spring loaded latching
member 408 includes a circular void in the shaft 112, a metal ball
bearing, and a spring. The diameter of the metal ball bearing is
greater than an opening in the circular void. When the ball bearing
is loaded against inner side of the circular void by the spring,
part of the ball bearing protrudes through the circular void and
extends outward from the shaft. When sufficient pressure is exerted
against the spring loaded latching member 408, the ball bearing may
retract into the shaft 112. It will be clear to those of ordinary
skill in the art having the benefit of this disclosure that other
latching mechanisms may also be used, including lever assemblies,
snaps, and other similar devices.
The head 100 may be selectively attached to the hip cup extraction
apparatus 101 so as to permit heads of different diameters to be
used with the same hip cup extraction apparatus. The first end 410
of the shaft slides into the hip cup extraction apparatus aperture
106. As the head 100 slides onto the hip cup extraction apparatus
101, the tip 418 of the semicircular cutting blade 406 passes
through the three sided void 110 so as to allow the head 100 to
pass completely onto the hip cup extraction apparatus 101 without
any mechanical interference. When the hip cup extraction apparatus
aperture 106 passes over the spring loaded latching member 408, the
spring loaded latching member 408 is depressed. Once the spring
loaded latching member 408 reaches the cylindrical detente 116, the
spring loaded latching member 408 extends into the cylindrical
detente 116, thereby latching the head 100 to the shaft.
Turning now to FIG. 5, illustrated therein is one embodiment of a
method 500 for removing a prosthetic hip cup from a pelvic bone. At
step 502, a hip cup removal apparatus is provided. In one
embodiment, the hip cup removal apparatus comprises a shaft, a
semicircular cutting blade, a selective detachable, semispherical
head, and a three sided void disposed along the semispherical head.
At step 504, the semispherical head is inserted into a cup section
of the prosthetic hip cup. At step 506, an optional impaction force
may be applied to the hip cup removal apparatus to initiate a
cutting action by the semicircular blade around the hip cup.
The hip cup removal apparatus is rotated, at step 508, such that
the semicircular cutting blade passes about the hip cup. At step
510, the hip cup removal apparatus is rotated until the hip cup can
be removed at step 512. In one embodiment of the method 500, the
hip cup removal apparatus may be pivoted along an axis such that
the semicircular cutting blade may pass completely about the hip
cup. In a further embodiment of the method 500, a plurality of
semicircular cutting blades--including a starter blade and a
finishing blade--may be used in removing the hip cup.
Turning now to FIG. 6, illustrated therein is one embodiment of a
hip cup extraction device 600 comprising a head 100 coupled to a
shaft 112, where the head 100 has been inserted into a hip cup 405
contained in a pelvic bone 401. In the embodiment of FIG. 6, the
hip cup extraction device 600 is configured with a starter blade
601 that may be used to cut around the outer rim of the hip cup 405
in order to remove the denser bone of the pelvic bone 401. The hip
cup extraction device 600 may be rotated about a first axis 602 and
pivoted about a second axis 604 in such a way that the starter
blade 601 cuts around hip cup 405.
Turning now to FIG. 7, illustrated therein is another embodiment of
a hip cup extraction device 700 comprising a head 100 coupled to a
shaft 112, where the head 100 has been inserted into a hip cup 405
contained in a pelvic bone 401. In the embodiment of FIG. 7, the
hip cup extraction device 700 is fitted with a finishing blade 701
that may be used to cut around the inner surface of the hip cup 405
to complete the bone removal process. The hip cup extraction device
700 may be rotated about a first axis 702 and pivoted about a
second axis 704 in such a way that the finishing blade 701 cuts
around hip cup 405.
In the foregoing specification, specific embodiments of the present
invention have been described. However, one of ordinary skill in
the art appreciates that various modifications and changes can be
made without departing from the scope of the present invention as
set forth in the claims below. Thus, while preferred embodiments of
the invention have been illustrated and described, it is clear that
the invention is not so limited. Numerous modifications, changes,
variations, substitutions, and equivalents will occur to those
skilled in the art without departing from the spirit and scope of
the present invention as defined by the following claims.
Accordingly, the specification and figures are to be regarded in an
illustrative rather than a restrictive sense, and all such
modifications are intended to be included within the scope of
present invention.
* * * * *